In passing from the sphere of politics to the serener region of literature, art, science, and philosophy, there is an increasing difficulty in estimating youth by years and an increasing necessity to estimate it by qualities. One thing, however, is certain,--that the invention of new methods, the discovery of new truth, and the creation of new beauty,--intellectual acts which are among the most-important of historical events,--all belong to that thoroughly _live_ condition of mind which we have called young. In this sense of youth, it may be said that Raphael, the greatest painter of moral beauty, and Titian, the greatest painter of sensuous beauty, were both almost equally young, though Raphael died at thirty-seven, while Titian was prematurely cut off by the plague when he was only a hundred. These, of course, are the extreme cases. But, it maybe asked, were not the greatest poems of the world, the "Iliad" of Homer, the "Divina Commedia" of Dante, the "Paradise Lost" of Milton, the creations of comparative old age? The answer to this question is, that each was probably organized round a youthful conception, and all were coextensive with the whole growth and development of their creators. Thus, we do not call Milton old when he produced "Paradise Lost," but when this mental growth was arrested; and accordingly "Paradise Regained" and "Samson Agonistes," works produced after his prime, are comparatively bleak and bare products of a withering imagination and a shrunken personality.